This sounds a lot like https://xkcd.com/793/ - "and then add some secondary terms to account for <complications I just thought of>."
They lost contact 105 minutes into a 120 minute, 2.5 mile descent. The release point for that descent was well known, and currents estimated closely enough to allow the sub to descend close enough to the shipwreck that the submersible's thrusters could move it very slowly to viewing locations.
They don't know what happened to cause it to lose contact more than a quarter mile above the ocean floor. They didn't know whether it went neutrally buoyant at that point, whether it ascended quickly, or slowly, or stayed near the bottom of the ocean and continued looking at the Titanic and only later drifted off course - they've done that before. Those ocean currents, unknowns, and distances are large; merely pulling the release point from a GPS track does not suddenly make the search point tiny.
This sounds a lot like https://xkcd.com/793/ - "and then add some secondary terms to account for <complications I just thought of>."
They lost contact 105 minutes into a 120 minute, 2.5 mile descent. The release point for that descent was well known, and currents estimated closely enough to allow the sub to descend close enough to the shipwreck that the submersible's thrusters could move it very slowly to viewing locations.
They don't know what happened to cause it to lose contact more than a quarter mile above the ocean floor. They didn't know whether it went neutrally buoyant at that point, whether it ascended quickly, or slowly, or stayed near the bottom of the ocean and continued looking at the Titanic and only later drifted off course - they've done that before. Those ocean currents, unknowns, and distances are large; merely pulling the release point from a GPS track does not suddenly make the search point tiny.